US2878588A - Air pressure demonstrator - Google Patents

Description

March 24, 1959 Filed June 8, 1954 L. P. GREGORY AIR PRESSURE DEMONSTRATOR 2 Sheets- Sheet 1 LOUIS P GREGORY ATTOR NE Y5 March 24, 1959 Filed June 8; 1954 L. P. GREGORY AIR PRESSURE DEMONSTRATOR 2 Sheets-Sheet 2 INVENTOR LOUIS P GREGORY ATTORNEYS United tates Patent AIR PRESSURE DEMONSTRATOR Louis P. Gregory, Gainesville, Fla.

Application June 8, 1954, Serial No. 435,384 7 1 Claim. (Cl. 35-49) (Granted under Title 35, U. S. Code (1952), see. 266) area under high pressure and with a second area under low pressure, given the opportunity, the air in the first area tends to escape to the area under low pressure, until the pressure in both areas are equal, or at equilibrium. While this law of physics is generally committed to memory by the student, it is often beneficial to clearly understand the principle by means of a visual showing of its effect. To provide such means, the instant invention has been devised.

A primary object of the invention is to provide a training means to visually illustrate a law of physics.

Another object of the invention is to provide a device that will illustrate the principle that air under pressure in two or more chambers tends to equalize by passing from the high pressure chamber to the low pressure chamber until equilibrium is attained.

Another object of the invention is to provide a simple, mechanical device which is divided into two or more chambers, with controlled connecting passageways therebetween, permitting retention of air under pressure in one chamber, and upon release of the control means, enabling the air to pass into the next chamber until pressure in both chambers is equal.

A further object of the invention is to supply gauge means to the device to visually illustrate the change in pressure taking place as the air travels from one compartment to the next one.

And another object of the invention is to provide a device that is inexpensive to manufacture, that is desirable in design and is eflicient to illustrate the intended principle.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood -by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 illustrates a preferred form of the invention in perspective,

Fig. 2 is a vertical section of the air pressure demonstrator and shows the valve control structure.

Fig. 3 is a section taken on line 3-3 of Fig. 2, and

Fig. 4 is a perspective view, partly in section, illustrating another form of the invention.

Referring to the form of the invention illustrated in Figures 1 to 3, the air pressure demonstrator is designated by numeral 10 and comprises an enclosed container of any suitable material. While container 10 may be of metal or wood, it is generally preferred to use a clear plastic material. Where the demonstration is intended 2,878,588 Patented Mar. 24, 1959 merely to illustrate the change in air pressures by observation of the gauges, as presently will be described, metal or wood will suffice. However, it is often desirable to illustrate the experiment by showing the air under compression being admitted to the container. In this event, some light material, such as cotton or paper would be placed within the container. Air under pressure would agitate this material and it would therefore be necessary to provide means to make this action visible. A transparent plastic container, or one with a clear plastic top, would satisfy these requirements.

Container 10 is rectangular in form and comprises opposed sides 12 and 14, base 16 and cover 18. The interior of the container is provided with a transverse wall or partition 20 extending between the opposed sides 14 and terminating at base 16 and cover 18 to provide a sealed fit whereby no leakage of air between chambers 22 and 24 could occur.

Transfer of compressed air is controlled by a valve member 26. Member 26 comprises an L-shaped conduit with the vertical leg'28 depending into chamber 22 and the horizontal leg 30 extending over chamber 24 and terminating in a valve 32. Valve 32 comprises a valve housing 34 threaded on the interior thereof at 36 and including a tapered valve seat 38. Valve stem 40 extends in housing 34 in threaded engagement therewith and is adapted to seat at 38 to close the valve. Stem 40 is provided with a reduced diameter shaft 42, permitting compressed air to escape through aperture or outlet 44 connecting with passageway 46 in conduit legs 28 and 3t).

Tubular studs 48 and 50 extendupwardly from chambers 22 and 24, respectively and are provided with passageways 52 to connect with the respective chambers. Gauge means, such as rubber balloons 54, are connected to studs 50 to provide the means for observing air pressure as supplied to the device.

Inlet conduits 56 and 58 are supplied to container 10 to connect with chambers 22 and 24. Check valves (not shown) are provided and air under pressure is admitted to either chamber by means of the conduits.

To demonstrate the problem, compressed air is admitted to chamber 22 or to chamber 24. Valve 32 is closed, and assuming compressed air is admitted to chamber 24, none of it will escape to chamber 22 when the valve is in the closed position illustrated. At this time, the balloon gauge 54, connecting with chamber 24, will inflate. Upon rotation of valve stem 40, shaft 42 will move away from valve seat 38, permitting the air under pressure to escape to passageway 46 and into chamber 22. As the pressure between the two chambers equalizes, the balloon indicator gauge 54 connected to stud 50 will deflate, while balloon 54 on stud 52 will inflate. When the air pressure in each chamber is equal, equilibrium will have been reached and no further transfer takes place. Both balloons 54 will then be equally inflated. Obviously, were the air pressure in chamber 22 greater than that in chamber 24, flow of compressed air would be in the opposite direction.

The principle of the invention is not limited to the embodiment just described, and is capable of being carried out in other forms. Fig. 4 represents a modification of the structure of Figs. 1 to 3 and is designed to illustrate the same principles.

Container 60 is similar to container 10 and includes opposed sides 62 and 64, base 66 and cover 68. Transverse partition 70 is similar to partition 20, except that a door 72 of plastic or the like, is provided and is hingeably mounted with center return type hinge 83 and can therefore swing in either direction into chamber 74 or chamber 76. Latch 84 is a manually operated push latch which locks the door in pressure tight relation with the partition 20. In this form, door 72 comprises the valve control between the two chambers and is mounted in air-' tight relation. Such mounting means are conventional and need not further be described. Low pressure gauges 78, mounted on supports 80 connecting with chambers 74 and 76, visually illustrate the air pressure in the chambers.

The operation is similar tothe operation described in the first form of the invention. Door 72 is maintained closed by latch 84. When the desired amount of compressed air has been supplied to one chamber, as indicated by gauge needle 82, door 72 is unlatched by pulling up on latch 84, causing the door to swing open towards the chamber at the lower pressure. When equilibrium is attained, the door again closes because of the center return hinge 83.

This form of structure? can also be used in a slightly ditterent manner by having door 72 open only in one direction, as for example, into chamber 76. In this instance, air under pressure is first brought into chamber 76. Since chamber 74 is at atmospheric pressure, door 72 remains closed. Compressed air is then brought in to chamber 74. When the pressure in this chamber becomes higher than the pressure in chamber 76, door72 will open and remain open until pressure in the two chambers becomes equal.

The invention is capable of many adaptations. Door 72 can be replaced by a flexible diaphragm, and othe forms of valve structures maybe substituted.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claim the invention may be practiced otherwise than as specifically described.

What is claimed is:

An air pressure demonstrator comprising a container, a

transverse wall dividing said container into two chambers, means connected to each chamber to increase or decrease the gas pressure therein; means connected to each chamber to indicate changes in gas pressure, said container and wall being made of a translucent material, a door hingeably mounted in said dividing wall, said hingeable mounting being of the center return type, and said door when unlatched will swing open upon excess of air pressure in one chamber relative to the other, said door being positioned in one corner of said transverse dividing wall, said dividing wall having a cutout for said door, said cutout being substantially the same size as the door and permitting said door to swing into either chamber, said door being made of an opaque material substantially the same thickness as the dividing wall, and capable of swinging open into either chamber, said door forming a pressure tight seal with said dividing wall when aligned flush with the surfaces of said wall and said door being secured in said pressure tight position by suitable latching means.

Watson: Text Book of Physics, p. 143, chapter 127, Expansive Power of Gases, published 1920.

Science Laboratory Equipment Catalog No. 244 of Chicago Apparatus Company, page 272, Fig. 169 R, published 1933. i

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